Apparatus for dissolving silicate of soda



June 17, 1930. EDGERTON 1,763,845

APPARATUS FOR DISSOLVLNG SILICATE OF SODA Filed Oct. 6. 1927 warren sraras euaara co PEL'NV r raraur orrica B. 0F NARBEBTH, PENNSYLVANIA, ASSIGNOR '10 PHILADELPHIA 0F PHILADELPHIA, PENNSYLVANIA, A CQBPORATION' OF APPT'US FOR DISSGLVING SILICA'EE 0F SODA.

Application filed October a 1927. Serial No. 224,353.

This invention relates to an improved apparatus for dissolving silicates, particularly sodium silicate.

' As is well @own to those skilled in the art, the preparation of solutions of silicate of soda has presented numerous difiiculties due to the inherent characteristics of the glass from which the solutions are made. At ordinary temperatures the hard, glass-like, coercial sodium silicate is practically insoluble in water, By the application of heat, however, solutions of sodium silicate can be made, but in applying the heat other difliculties are encountered, especially when large scale operations are desired.

It is the principal object of my invention, therefore, to provide an apparatus for dissolving the sodium silicate, or other like material, rapidly and economically upon a lare. scale.

further object of the invention resides in the provision of an improved means for causing a continuous circulation of the solution and one in which the heating medium itself, referably steam, is utilized to create or in uce such circulation throughout the entire mass.

lln this connection it should be borne in mind that the condition most favorable for the solution of sodium silicate is an excess of the silicate with respect to the dissolving water. In other words, the tank or container in which the solution is being prepared is kept constantly filled with a charge of glass, wh1ch charge is substantially greater than it would be possible to dissolve in the quantity of waterpresent.

My invention also contemplates the provision of an apparatus which requires no mechanical agitating means and which is simple and inexpensive to construct and maintain, and which may be readily assembled or disassembled for cleaning or repairs, well as one which can be operated by comparatively unskilled labor and the employment of a minimum number of men.

it is also an object of the invention to provide an aparatus in which the troubles incident ydrolysis will be obviated or Ihe foregoing, together with. such other objects as may appear hereinafter, or are incident to my invention, are obtained in the manner now to be described in connection with the preferred form of apparatus illustrated on the accompanying drawing, in whichi Fig. 1 is a somewhat diagrammatical elevation of the apparatus with the dissolving tank shown in section, and

Figs. 2 and 3 are enlarged views of a detail of the apparatus.

The form of the apparatus herein disclosed includes a tank 1 having a convex bottom 2 and supported in any desired man ner, as by means of the blocks 3 and brackets 4:. The top 5 is also convex and is provided with a central opening 6 adapted to be tightly closed by a cover plate 7 which can be held in place in any desired manner.

Near its bottom the tank is provided with a silicate supporting screen 8 which createsa collecting chamber 9 between itself and the bottom 2. The screen may be supported as desired, as by the channels 10 and an le I1. Access to the bottom of the tank For the purpose of cleaning or repairs is had through the manhole 12 suitably closed by the cover 13-. Substantially in the center of the tank is a standpipe 14 which projects upwardly from the bottom 2 through the screen 8 substantially to the top of the tank, the upper end being positioned and braced by means of the angles 15. The lower portion of the standpipe 1 1 is provided with a series of slot-like openings 16, arranged in annular roups of eight holes each, beginning at su stantially the point where the plane of the screen intersects the pipe A screen 17 is wound around the pi e to cover the holes 16 and is held in place by the bands 18. @uly the up er end of this screen is illustrated in the drawing, but it will. be understood that it is continued downwardly to cover all of the'openings with a band 18 between each group of holes. At the'top the standpipe is, of course, open to the tank, and immediately above the opening l arrange what may be termed a combined spreader and guard supported by suitpreferably 38 projecting toward the opening 6.

Below the screen 8 is located a bottom sampling line 19 and near the top of the tank a second or' emergency sampling line 20.

Steam for heating the contents of the tank is introduced by means of an injector 21 which discharges through the bottom 2 upwardly into the standpipe 14, the steam being supplied through the pipe 22 in which is located a shut-off valve 23 and a check valve 24. A steam separator 25 is also located in the steam line 22 for a urpose which will appear hereinafter should a flow of steam take place in the reverse direction.

Water is sup lied to the tank through the line 26 in whic is located a shut-off valve 27 and a check valve 28. The injector 21 communicates with the bottom of the tank through a portion of the line 26 and the connecting pipe 29.

The tank is provided near its top with the pressure relie pipe 30 which carries the steam gauge 31 and the shut-off valve 32. At the bottom of the tank is arranged the discharge or blow-off pipe 33 through which the solution can be withdrawn under the control of the shut-off valve 34.

The operation of the device is as follows:

. the incoming stream of glass and prevent any of it from falling into the interior of the pipe. The valve 27 is then opened and the tank filled with water, after which the cover 7 is securely fastened in place and the pressure relief valve 32 closed. The blowoif valve 34 and the valves in the sampling lines are also closed and steam is turned on by opening the valve 23.

The injector 21 differs from the ordinary form of injector most commonly in use in that it is designed to pass a large amount of steam in relation to the amount of liquid, since the apparatus requires as much steam as possible in order to bring up the temperature of the solution as Iluickly and. evenly as possible. After the ta 7 has een filled with water, the valve 27, of course, is closed, and, as the steam passes upwardly, it creates or induces a circulation downwardly through pipe 26 and across through connecting pipe 29. The contents of the chamber 9 consequently are. steadily withdrawn during the operation of the device and passed upwardly through the interior of the standpipe 14 along with the heating steam coming in through the injector 21. The major portion of the circulation is created in this manner, although there will also be circulation inwardly into the pipe 14 through the openings 16. The screens 8 and 17 serve to keep the smaller particles of glass from entering the circulating solution. When the hot column of ascending solution strikes the lower cone of the spreader 35 it is deflected and evenly distributed outwardly over the entire upper surface of the glass in the tank.

In this way it is possible to maintain a solution of substantially constant density throughout the entire tank without local over-concentration at any point, a feature which is of great importance, since it is essential to withdraw the solution at just exactly the right moment if certain difficulties well known to the art are to be avoided.

When a test through the sampling line 19 shows that the proper density has been reached, the steam is shut off and the valve 34 opened. The liquid contents of the tank are then blown off through the pipe 33 under the accumulated pressure within the tank which may sometimes be upwards of one hundred pounds. After the solution has been discharged, additional quantities of glass are introduced at the top and the tank refilled with water. In this way the apparatus may be said to be operated batch-wise and the operation can be substantially continuous.

It will be understood, of course, that the cover plate 7 should not be removed if there be any pressure remaining in the tank, as is frequently the case, such pressure ranging as high as fifty pounds. This pressure can be reduced either by introducing cold water through the pipe 26, provided, of course, that the water is above the pressure of the steam, or by relieving the pressure through the pressure relief pipe 30 and the valve 32.

It occasionally happens that the pressure of the steam within. the tank may be above the pressure coming in through the pipe 22, due to a sudden large demand upon the boiler or'other source of supply. In this event, there would be a tendency for the solution to back up through the pipe 22 and this is prevented by the check valve 24. Should steam escape in a reverse direction through pipe 22, any liquid entrained with it would be separated by the separator 25 and collected in the tank portion 39.

The screen 8 will gradually become clogged with dirt or extraneous matter, and this can be determined by using the top sampling line 20, for just as soon as the screen ceases to function freely, there will be quite a marked difference in density between the solution at the bottom in the chamber 9 and the solution at the topof the tank.

It will, therefore, be seen that I have provided an appartus for creating a continuous circulation throughout the mass by withdrawing solution from the bottom and passing it upwardly to the top of the mass and distributing it evenly thereover. The heating steam is used to cause this circulation because it is passed upwardly through a confined column of the liquid (the column within the standpipe 14).

It is to be understood, of course, that between each batch there is a large amount of glass remaining in the tank, as it is in no case intended to dissolve all of the glass present in one operation. The period of the cycle will, of course, vary, but we have found in practice that for a tank which will accommodate about a ten foot depth of glass, it will be in the neighborhood of an hour and twenty minutes.

The apparatus has no moving parts, which is a feature of great advantage because the small particles of glass in the liquid have a very abrasive effect upon any. moving or hearing parts.

1. A silicate dissolver comprising in combination, a tank, a silicate supportingscreen near the bottom of said tank, a standpipe in the tank, openings in the lower portion of the standpipe communicating with the silicate chamber above the screen, and means for introducing a heating medium into the bottom of the standpipe below said openmgs.

2. A silicate dissolver comprising in combination, a tank, a silicate supporting screen near the bottom of said tank, astandpipe in the tank, openings in the lower portion of the standpipe communicating with the silicate chamber above the screen, a circulating connection from a point in the bottom of the tank outside of the standpipe to a point within the bottom of the standpipe, and steaminjector means rojecting upwardly through the bottom oi the standpipe and drawing fluid through said connection.

3. A silicate dissolver comprising in combination, a tank, a slhcate supportin screen.

near the bottom of said tank, a standpipe in the tank, openings in the lower portion of I the standpipe communicating with the cilicate chamber above the screen, a circulating connection from a point in the bottom of the tank outside of the standpipe to a point within the bottom of the standpipe, steam injector means projecting upwardly through the bottom of the standpipe and drawing fluid through said connection and a distributor at the top of the standpipe having an apex rojecting downwardly toward the center 0 the standpipe.

4. A silicate dissolver comprising in combination, a tank, a silicate supporting screen near the bottom of said tank, a standpi e, an opening in the lower portion of t e standpipe communicating with the silicate chamber above the screen, a circulating connection from a point in the bottom of the tank outside of the standpipe to a point within the bottom of the standpipe, and means for injecting a heating and circulating medium into the bottom of the standpipe.

5. A distributor for a silicate dissolver of the character described comprising opposed cones with outwardly facing apices and an annular concavity on oneface surrounding the apex.

In testimony signed by name.

LLOYD B. EDGERTON. 

